Biferi, M.-G. | bioRxiv Science

bioRxiv2026

Restoring Parkin Function: An AAV Gene Therapy Approach for Early-Onset Parkinson's Disease

BackgroundBiallelic loss-of-function mutations in PRKN gene (encoding Parkin protein) cause early-onset Parkinsons disease (EOPD). Parkin is a crucial component of PINK1-Parkin pathway, which marks damaged mitochondria for degradation via mitophagy. Without functional Parkin, damaged mitochondria accumulate, causing oxidative stress and neurodegeneration. ObjectiveInvestigate Parkin gene replacement via AAV gene therapy as a potential treatment for Parkin-dependent EOPD. MethodsWe initially validated phosphorylated ubiquitin Ser65 (pUbSer65) as an indicator of Parkin-mediated mitophagy initiation. We evaluated AAV-mediated PRKN replacement (hereafter, AAV-Parkin) in a Parkin knockout neuroblastoma cell line (SH-SY5Y cells) and feasibility of delivery in mouse and rat models. ResultsOur research showed pUbSer65 signal was reduced in Parkin-KO SH-SY5Y cells when compared to wild-type cells after mitochondrial stress, indicating deficiency in initiation of mitophagy. AAV-mediated human PRKN gene replacement successfully restored these pUbSer65 levels in knockout cells. We saw restoration in patient-derived fibroblasts following AAV-Parkin overexpression. We developed a translatable gene therapy approach using rodents. We demonstrated the feasibility of delivering AAV-Parkin directly into the substantia nigra (SN) of wild-type rats. Using an AAV1 capsid with Ef1a promoter, we achieved dose-dependent Parkin expression and identified a well-tolerated dose. We also evaluated multiple promoters in a proprietary Spark100 capsid, finding Ef1a and Synapsin1 (Syn1) were most effective for transducing dopaminergic neurons in the SN of mice without causing adverse effects. These findings established a well-tolerated vector dose and an optimal capsid-promoter combination. ConclusionsOur results support the potential of AAV-Parkin gene therapy as a disease-modifying approach for Parkin-deficient EOPD. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/737487v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@16dd13corg.highwire.dtl.DTLVardef@c3dfcdorg.highwire.dtl.DTLVardef@19a310dorg.highwire.dtl.DTLVardef@a66f2_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

Targeted-SMN insufficiency in Skeletal Muscle Stem Cells mediates non-cell autonomous loss of motor neurons at long term

Spinal Muscular Atrophy (SMA) is due to a deficit in SMN protein encoded by the SMN1 gene. SMN-targeted disease modifying treatments have greatly improved the clinical outcomes of this neuromuscular disease. However, uncertainties remain regarding their long-term efficacy and non-neuronal tissue involvement in disease progression. We found that SMA type II patient muscles display a reduced number of quiescent PAX7+ Muscle Stem Cells (MuSC). In SMA mice, we showed that SMN is an important regulator of myogenic progenitor fate during early postnatal growth. In Pax7 Cre-driven conditional knockout mouse models, we demonstrated that high levels of SMN are required to ensure the maintenance of the quiescent MuSC pool in adult muscle. We further established that depletion of SMN-deficient MuSC yielded neuromuscular junctions remodeling followed by a non-cell autonomous loss of motor neurons in the long term. Overall, our findings demonstrate that MuSC are a crucial therapeutic target for SMA treatment. HIGHLIGHTSO_LISMN regulates myogenic lineage progression and quiescent MuSC pool establishment during postnatal growth C_LIO_LIBoth Smn alleles are necessary for the survival of quiescent MuSC in adult muscle C_LIO_LIDepletion of SMN-deficient MuSC leads to NMJ remodeling and non-cell autonomous loss of MN C_LI

pathology↗